Sex steroid levels during treatment of endometriosis.

Ovarian endocrine function in endometriosis was studied in 19 women before, during, and after treatment with danazol. Striking abnormalities were seen during treatment. Serum estradiol (E2) and testosterone (T) levels increased markedly, while follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin were unaffected. Direct interference of danazol in the assays for E2 and T was excluded by in vitro experiments. The most likely explanation for the isolated alterations in peripheral hormone levels is that danazol affects the carrier proteins in the circulation. However, other explanations are also possible and cannot be excluded at this stage.